


Riptide

by fromthefiresofhell



Category: Supernatural
Genre: (the previous of which was totally accidental), Alternate Universe- Mermaids, Art, Bottom Dean, Bottom Dean Winchester, Dean Whump, Egg Laying, Eggpreg, Eggs, F/F, F/M, Fluff and Angst, Happy Ending, Hurt Dean Winchester, I'm not even sorry about that either, I'm so bad at holding angst for awhile cause I start to upset myself, Illustrated, Illustrations, M/M, Mating Cycles/In Heat, Mating Rituals, Merfolk AU, Merman Castiel, Merman Dean, Mpreg, Not Beta Read, Porn With Plot, Porn with Feelings, Pregnant Dean, Self Confidence Issues, The Author Regrets Nothing, Top Castiel, True Mates, and the whump lasts for about 1k words, im such a wuss for my otps, mermaid au, no worries this ain't no twist and shout, or anything of the like, really though it's probably gonna be like 15000 words of porn, theres probs gonna be some gross fluff, this is literally just an excuse for me to write interspecies (?) non-human smut
Language: English
Status: In-Progress
Published: 2014-05-19
Updated: 2014-07-07
Packaged: 2018-01-25 16:37:45
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 17,411
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1655255
Author URL: https://archiveofourown.org/users/fromthefiresofhell/pseuds/fromthefiresofhell
Summary: <blockquote class="userstuff">
              <p>As a general rule, Dean avoids the shallows.</p><p>It’s not that he has a problem with his brightly colored cousins, it’s just that they get on his nerves if he’s around them for more than a handful of breaths. Which, Dean guesses, means he does actually have a problem with them.</p>
            </blockquote>





	1. Ripple

**Author's Note:**

> This was supposed to be mermaid smut celebrating my 3000th follower on tumblr, but it got a little more plotty than I originally intended. Depending on the reaction, I'll continue it.
> 
> I just realized that while some of the lingo is self explanatory, some stuff (like mating rituals, which all merfolk know and never have to explain to each other) might be vague. I posted a glossary to my tumblr (celestial-sexhair.tumblr.com/post/86242454950/riptide-glossary). Feel free to shoot me an ask if you need clarification on something.

As a general rule, Dean avoids the shallows.

It’s not that he has a problem with his brightly colored cousins, it’s just that they get on his nerves if he’s around them for more than a handful of breaths. Which, Dean guesses, means he does actually have a problem with them. It’s just that they’re always _singing_ or _dancing_ and their hair is always up in those ridiculous braids and woven with bits of kelp or twine or anything else they can possibly get in there. Many of them, especially females, pride themselves on having as many braids as they can and the sheer _number_ of braids combined with their ridiculous frilly fins makes Dean dizzy just looking at them. 

Kelp folk like himself stick to the basics- a belt for a weapon and the occasional small trinket. Dean has his dagger and the protection charm his mother gave him secured around his waist with thick kelp. Other than the single tooth he wears on a cord around his neck, that’s it. Those two things impede his swimming enough, he can’t possibly imagine trying to maneuver through the kelp weighed down by the amount of decorations the reef folk wear- pearls and shells and ropes of rocks. It seems that they’re willing to attach anything that strikes their fancy to their bodies (including, in one or two shocking cases, live fish.)

But now Dean finds himself leaving the comfort of his kelp forest and swimming towards the very reef he works so hard to avoid.

It only happens once every two seasons, the itch under his scales that means it’s time to mate. The first few times it happened, Dean ignored it, because the only other kelp folk for many lengths is Sam. It wasn’t until a passing clan of sea folk happened by during the end of his mating season that he discovered the reef folk could give him pups instead of just being a nuisance.

That’s where they were headed, the clan leader had said. The reef. He told Dean that pups sired by different clans richened the blood. It was because of this that a handful of female sea folk propositioned Dean in the few light-darks that they hung around, but he refused their offers. His own mating season was ending and any matings he performed wouldn’t stick. He felt bad turning away one particularly persistent female- Lissah, she called herself- but mating would have been a waste of her energy and his time 

Sea folk are relatively peaceful, but Dean still didn’t like them in his territory, so he was happy to see them go. They left him with a large turtle to thank him for his hospitality. The meat was tender and rich and now Dean uses the empty shell to collect tokens that could woo a potential mate. He carries the best of those tokens on his belt now, safely wrapped in a pouch of kelp.

Normally when traveling such a great distance, Dean would drift along lazily on the current and stop often for meals and to rest, but now he powers through the waters with a purpose. The itch excites him, yes, but it’s more the prospect of who awaits him at the reefs that propels him.

Dean only sees Sam once or twice a season now that he’s grown up and moved to his own forest. Neither of them can risk being away from their territory for more than a few light-darks, there are plenty of other creatures who would snap up the chance to move in, but the last time they saw each other Dean shared what the sea folk told him. Sam agreed that a flamboyant mate was better than none at all and he and Dean decided to meet up with each other once arriving at the reef. 

Dean’s glad Sam will be there, at least he’ll have one familiar face to relate with.

Dean perks up as the first few notes to the reef folk’s songs reach his ears. Their music carries far during the mating season, he’s still a whole light-dark away, but that’s two light-darks closer than he was when he began his journey. The waters are warmer here as opposed to the cool depths of his forest and Dean can’t decides if he likes it. It’s certainly a nice change from wrapping himself in kelp during the cold season, but his fins twitch and ripple uncomfortably in the unusual heat.

The sky eye is sinking towards the sea, so Dean veers off his course to find a suitable cave to spend the dark in. He doesn’t mind hunting during the dark at home in his forest- in fact, he prefers it since his dark vision is much better than most of his prey's- but out here in the open waters, things bigger and far more dangerous than him come out in the dark. Better to sleep through it than risk having his tail bitten off.

 

x

 

Castiel flares his fins and opens his mouth to sing.

Mating season only began a few light-darks ago, but already Castiel is beginning to worry. The majority of the sought-after sires have already holed up in their chosen alcove with a mate. This is the first mating season Castiel has an alcove for, but no one has responded to his song. 

Passing reef folk give him strange looks when he sings to them. Castiel knows his song is unusual, deep and thrumming where most of his kind’s music is light and high, but his fins are an acceptable size, if not bigger, and his tail shines and his alcove is spacious and protected. By all accounts, he should have a mate by now.

A young, brown spotted female by the name of Hester drifts lazily by, enjoying the light on her scales, but when Castiel starts to sing she darts away. He scowls. On a warm light like this, this shallow part of the reef should be crawling with reef folk enjoying the sky eye’s heat. They seem to form a huge bubble around him, purposefully taking the long way around his alcove to avoid him and his song.

Movement to his left catches Castiel’s eye and he almost opens his mouth to sing, but a flash of red makes him sigh and kill the notes forming in his throat. It is just Anael. Still, though, Castiel smiles as she approaches. She never fails to cheer him up. 

“Hello, brother,” Anael says, sliding along the reef towards him. She looks beautiful in her mating attire. Her long hair is plaited into hundreds different braids that must have and must have taken a whole light, especially since she wove white feathers in that contrast strikingly with the copper tone, and an stunning headdress of smooth rocks and white sea stars sits nestled amongst the wispy locks that escaped from her braids. The net of pearls and pale shells draped over her shoulders clinks together pleasingly every time she moves.

She is, Castiel thinks as Anael settles on her tail on the coral, the most radiant of all the females. 

“Anael.” He sinks down beside her on the shelf, brushing his hip fin against hers in greeting. “You look very attractive.”

Anael giggles, a lofty sound that Castiel is not used to, and grabs one of her braids, twirling it between her fingers. “You think so?”

Castiel nods. “Have you received any propositions yet?”

Twisting, Anael flips her fluke out from under her to show her brother a ring of tiny fish skulls dangling from twine tied around the end of her tail. 

Castiel hums and reaches out to tap one of the skulls. “Impressive. Who offered them?”

“Michael,” Anael says with pride. Castiel’s eyebrows shoot up. Michael is next in line to be the clan leader. He has completed the trials, the circular scar in the middle of his back is proof of that, and will give Anael a strong pup (maybe even pup _s_ ) should she choose to mate with him.

“And you didn't accept him?”

“Not yet.” Anael slides her tail back underneath her to sit comfortably on the fold. Her cheek fins flick restlessly and she smooths her hands over her scales nervously. “I wanted to ask you what you thought first.”

Castiel cocks his head. “Michael is a strong warrior,” he says honestly. “He may seem detached sometimes, but he has a good heart.” He pauses to consider, watching a small school of round, flat fish dart past. After a while, he decides, “I believe it will be a good match.”

Anael chirps excitedly and flings her arms around Castiel’s shoulder in a rare sign of affection. He pats her back gingerly, perplexed at this sudden display of sororal love. Anael is usually calm and collected, though friendly, but she is never as outward with her emotions as this. It must be the mating hormones getting to her.

“It seems you had already decided on an answer,” Castiel says in amusement.

Anael shrugs and she pulls away, smiling. “I suspected you would approve, but was worried you would find him lacking.” She tilts her head curiously and leans forward, resting her chin in her hands. “What about you, Castiel? Any pretty tails catch your eye?”

Castiel frowns, good mood gone. “Plenty.”

“Were they not attractive enough for you?” Anael teases, never missing a chance to pick on her little brother. She pinches Castiel’s hip fin, getting a huff and her hand smacked away in return. Castiel, being the baby of the brood, was always the one to receive adoring fin pinches from older reef folk and even now, he hates having his fins touched for longer than a greeting brush. “Castiel, you must stop being so picky if you’re ever to find a mate.”

To Anael’s surprise, Castiel’s frown just deepens and he pushes off the shelf. “You should go,” he says abruptly. “You shouldn’t keep Michael waiting.”

“Castiel?” Anael glides over to her brother’s side and puts her hand on his shoulder, teasing tone replaced by a concerned one. “What’s wrong?”

Castiel shrugs her hand off. “Nothing.”

“Well, it’s obviously something.” Anael crosses her arms and sets her jaw in a face Castiel vividly remembers from when they were pups. It is her serious face, the one that means she’s not giving up until she gets what she wants. 

With Anael staring him down, it is hard to lie outright, but Castiel does not want to alert his sister of how much of a failure her brother and best friend is, so he twists the truth a little bit. Just a little.

“I don’t have enough decorations,” he says, speaking to the fish hovering over Anael’s shoulder instead of her. He would not be able to get the words out if he looked her in the eye. “I believe.”

Anael rolls her eyes. “It’s so like you to worry about such things, Castiel.” She pulls lightly on the string of shark teeth around his neck. “Don’t worry, brother, you have plenty of decorations. I’m sure you’ll woo a mate. Just give it time.”

“Yes,” says Castiel, looking up at the sky eye glaring down at him. He wonders what Anael will say when she discovers _exactly_ why he hasn’t been able to attract a mate. “Time.”

 

x

 

Dean arrives at the reef halfway through the next light.

The reef’s older pups, playing along the outskirts of the reef, gawk at him as he swims up. They whisper among themselves until the male watching over them hushes them and swims forward, a polite smile on his face. 

“Can I help you?” he asks. Dean is thankful he didn’t run into a guard. Reef folk are fairly open to other folk, but their guards are liberal with their spears around mating season. All those unfulfilled mating urges make them touchy. 

“Yeah.” Dean swallows, suddenly nervous. He’s never been one to let fear stop him, though, so he plows on. “Um, I live in the kelp forest that way,” he jerks his thumb behind him, “and there aren’t any more kelp folk around. Except my brother. Which would be,” he chuckles nervously, “Kinda weird. So…”

“I see.” The reef folk glances at the wide eyed pups behind him, then leans closer so they won’t overhear. “Have you mated before?”

Dean flushes despite himself and says gruffly, “Why?”

“I take that as a no, then.” At Dean’s narrowed gaze, the male holds up his hands peacefully. “I only ask because some folk don’t know our rituals. There’s been a lot of mix ups because of that, you know.”

“I’m fine, thanks.” He'd been a curious pup and his father hadn’t exactly been skimpy on the details. If there was one good thing about John, it was that he taught his sons all they needed to know about the ocean.

The male nods, then offers his hand. “Samandriel.”

Dean claps his arms together, gripping Samandriel’s elbow tightly in a formal greeting. “Dean.”

“Welcome to our reef, Dean.”

Dean sends a click towards the pups as he swims past, smiling when they scatter, chirping in confusion. Reef folk don’t have clicks, they don’t need them in their coral home. To Dean, on the other hand, his clicks are essential for navigating the tightly packed kelp he lives in.

As Dean swims into the main reef, he’s almost overwhelmed. The coral is brightly colored and bursting with life, swirling with schools of fish and reef folk. The songs of searching males pound at his ears and Dean flattens his cheek fins over his ears with a hiss. For the love of the sea, they could at least quiet down a little bit. It’s not like they need to woo mates that are leagues away.

Flattening his ear fins helps with the noise, so that’s how Dean keeps them. He glides through the reef at a leisurely pace, just taking everything in. He’s never actually been in the reef before, but it’s a lot more organized that Dean thought. There’s one main path running all the way down the reef, sheltered from the currents by the high walls of coral. Younger pups are playing here, watched closely by their mothers and fathers. Their tails are still unpigmented and their moves are hesitant and unsure; they can’t be more than two seasons old. 

Dean peers down each one of the alleyways splitting off from the main path as he swims down it. Most of them are designated to sleeping hollows or food storages, but one of them is definitely a healer and in another, a group of elders are talking lowly with each other. 

It isn’t until the end of the path that Dean sees the first searching male. He’s floating in front of his alcove, covered from head to fluke in strings of delicate snail shells and shaking his head to send his short brown braids rippling through the water. He looks so ridiculous that it takes all Dean has not to laugh outright. The reef folk aren’t hostile, but they wouldn’t take kindly to Dean ridiculing them. 

Dean turns and swims away quickly before the male can start singing to him. He’s too tired from his journey to start scoping out the selection now. It’s not like everyone suitable will disappear in one light-dark. The reef folk may care how pretty their mate’s voice is and how big his fins are, but all Dean needs is someone strong and healthy. They could be wearing dead fish and screeching like the wind for all he cares.

There are plenty of unused sleep hollows and Dean’s trying to find the most comfortable one when he thinks he hears someone yell his name, muffled through his ear fins. He lifts them and listens, and sure enough…

“Dean!” A hulking shadow falls across him and Dean looks up to see a figure looming up above the coral.

“Hey, Sammy,” Dean says, and that’s all he has time to say before he’s tackled by his kraken sized brother. He suffers through a few seconds of a rib-crushing hug before pounding on Sam’s back and wheezing.

“Sorry,” Sam says, pulling back with a smile. He looks good, clean-shaven and bright eyed, but his hair is longer than some of the females’ and he’s wearing… a pearl circlet?

Sam notices Dean staring and shrugs. “A pup gave it to me.”

“Uh-huh,” Dean says, unconvinced. “I still think you’re just secretly a female. The hair proves my point.”

Sam punches him lightly on the shoulder. “Whatever, Dean. When did you get here?”

“Earlier this light. You?”

“Two light-darks ago.” Sam gestures to the main path, barely visible through the columns of coral. “So what’ya think?”

“Honestly, I don’t know,” Dean says. “They’re all kinda… ridiculous.”

Sam grins his agreement. “Yeah, but they’re not that bad when you get to know them. Once you get past the singing."

Sometime about Sam’s tone makes Dean’s eyebrows rise. 

“Sammy,” he says knowingly. “You found yourself a female, didn’t you?”

“Um,” Sam says haltingly. “Not really. Well, I guess so, maybe, she’s- Dean, stop making that face!- she’s been coming around a few times each light. She hasn’t actually come up to me, though, so it’s not really official.”

“You did,” Dean says, grinning. “You totally did.”

“Yes! Alright, Dean, I found a female.” 

“I knew you had it in you, Sammy,” Dean says as Sam rolls his eyes. “I almost gave up hope a little while back, but you pulled through.”

“Dean, you’ve never mated either.”

“Minor detail,” Dean says dismissively, waving his hand. He settles into one of the empty sleep hollows, letting his tail droop off the edge and swish back and forth with the current. “So, tell me about her.”

Sam hesitates, says, “Well, her name’s Jess.”

“Jess?” Dean says. “That sounds more like a kelp folk name.”

“I think her full name’s Jessickah. Everyone just calls her Jess.”

“I can see why. Jess-ick-ah,” Dean says, rolling the word around on his tongue. The reef folk have long, complicated names that always feel strange on Dean's tongue. He's used to the short, clipped names of his own folk. “That’s one hell of a mouthful.”

“And she’s got these big blue-grey eyes, like the sky during a storm,” Sam continues, eyes getting wider as he speaks and ignoring Dean completely. “And long blonde hair and Dean, she only wears it in one braid and there are little crab claws in it, and her _tail_ , it’s so long and flowing and the color is just the right shade of purple-”

“Alright, lover boy. You’re making me sick.”

Sam huffs and pulls a face, but relents. “Yeah, yeah, alright. So, what about you?” He settles in the sleep hollow across from Dean, hulking form barely fitting in the space. “Are you going to woo a female? There aren't any alcoves left. You'll have to fight for one.”

“Nah.” Dean has no doubt he could take on a reef folk, even if spears are longer than daggers- especially now that they’re all decked out in heavy mating decorations- but that’s not what he had in mind. “I don’t think I’m gonna sire this year.”

“Mmm,” is all Sam says, but it’s a very loaded _mmm_.

“What?” Dean demands. “You don’t think I’d make a good father?”

“No! I mean, yeah you’d make a great father,” Sam adds when Dean squints dangerously. “But Dad wasn’t exactly the best role model.”

“Dad was great,” Dean snaps, then sighs and scrubs a hand over his face. He doesn’t want to have this fight right now. His scales still itch and he’s in a bad enough mood as it is, an argument with Sam won’t do anything to improve it. “I just don’t want to stick around after the deed. All this singing will drive me insane. Or deaf.”

“I’d like to stay,” Sam admits after a few beats. “It’d be nice, I think.”

“Hey, to each his own, Sammy.” 

Sam’s always been the more patient of the two, Dean will admit to that. Smarter, too. He’ll adapt nicely to reef life. Dean, on the other hand, likes his privacy. Everything here is too personal and crowded for him, he’d rather raise a pup alone in the kelp forest than here among faces he doesn’t know or trust. Kelp folk always raise their pups alone, searching males swim from forest to forest and usually never meet their pups. Even if they did offer to help raise the pup, they would probably get booted out of their mate’s territory for insulting their parenting skills. The only time two kelp folk would ever raise a pup together was if they were true mates. Like Mom and Dad. 

Dean’ll stick to what he knows. He’ll be able to raise the pup right, teach it all about life in the kelp forest. Hand to hand fighting skills, how to take down a shark, how to hunt a particularly cunning fish. None of this silly pearl-wearing, melody-singing, spear-jabbing crap.

Besides, he could always bring the pup for a visit with his Uncle Sam, the sea knows he’ll probably need a break. Unlike kelp folk, reef folk welcome, even expect, a sire’s help in rearing pups. That’s probably part of the reason Sam wants to sire instead of carry. He barely remembers Mom and the memories he does have a blurry and distant. Most of his childhood was spent with only Dad, who (while being a good father) _was_ a little tough on them. It made them the strong folk they are now. But this will be an opportunity for Sam to have a family. A complete one.

“I should get back,” Sam says, twitching his fluke to propel himself out of the sleep hollow. “The male next to me promised to defend my alcove so I could talk to you, but I don’t know how long that’ll last.”

Dean smiles and whacks his tail against Sam’s playfully. “See yah, Sammy.”

Dean watches Sam swim out onto the main path then flops down in the sleep hollow. He’s a little disappointed that he won’t be able to spend more time with Sam, but as long as he’s happy, Dean’s happy. He’ll have to make Sam introduce him to this Jess, she doesn’t actually sound half bad. 

Even though the sky eye is still high above the sea, it doesn’t take long for sleep to take him. 

 

x

 

Castiel has no more luck attracting a mate during the next light. If anything he has less. The reef folk are definitely avoiding his alcove now, which isn’t hard to do since it is so secluded. He thought it would be a good thing, a mate would be more likely to choose him if his alcove was more protected than most. But word must have gotten around about his song and his choice is backfiring on him.

Castiel has never been truly embarrassed before, but now he feels so ashamed that he only sings twice during this light. He remembers, as a pup, admiring his father’s beautiful song. It had been almost haunting in its rise and fall of notes, eerie like the sea during a storm, and Castiel recalls telling Anael that he hoped his song would be just like that.

Oh, if his father could see him now.

Anael does not come back to visit now that she has accepted Michael’s proposal. Castiel’s stomach feels sour whenever he thinks about it. In a few light-darks, Anael will emerge sated and happy and full of life, only to have her good mood ruined by the realization that Castiel is a disgrace. 

Instead of occupying himself rearranging his decorations or cleaning his alcove or braiding his hair, Castiel thinks. He is a good warrior, he is sure of that much. If his song is not appealing, if he can not benefit the clan by expanding it, he will be useful in some other way. He will be the best warrior he possibly can and protect the clan with his life. 

Pitying himself will not do anything. He will keep up appearances until the mating season is over, but he will not claim an alcove next year. There is no need to put himself through this miserable ordeal again. Not drawing attention to his song will not hide the fact that he is a failure of a mate, but it will not make him an outcast, either. After mating season, there will probably be a few light-darks of tension, but after that it will all go away. 

Plus, continuing to sing would drag Anael down with him. Females do not need mating songs, but the folk might begin to wonder. Since they share the same mother _and_ father, by all logic if there is something wrong with Castiel, there must be something wrong with Anael.

No, it will be better this way. Everyone benefits if Castiel does not sing.

Castiel has just come to this conclusion when a small group of males swims towards him. He braces himself for the inevitable whispers and sideway glances, but the group swims past him without so much as a fin twitch. Castiel spots Balthazar among the group, talking animatedly. 

The last time Balthazar was that excited, it was because a pup had gone and got herself locked in a giant clam shell. He gossiped about it for light-darks on ends.

Which means something has happened.

“Balthazar,” Castiel calls, swimming towards the group. He does not worry about his alcove, no one will take it now. Not with the stigma it carries.

Balthazar looks around, confused. He was so engrossed in talking, he did not even realize he had passed Castiel’s alcove. It is the quickest route between some places, off the main path it may be. 

Suddenly, Castiel is nervous. Balthazar has been his friend since he was a pup, but he is sure to have heard the rumors by now. Castiel has very few true friends, he is too formal for many reef folk, and losing Balthazar is something he can not imagine, now or ever. 

But Balthazar smiles the same cocky smile he’s always given Castiel upon seeing him, and swims to meet him halfway. Castiel lets out a breath of relief. 

“Hey, Cassie,” Balthazar says, perhaps softer than usual, and brushes his hip fin against Castiel’s. He knows well enough not to ask about how the mating season is going. 

“What happened?” Castiel asks, glancing over Balthazar’s shoulder at the males he was swimming with. They are looking at Castiel curiously, but not in disgust, like they are surprised he does not know yet.

“You haven’t heard?” Balthazar asks, grinning when Castiel shakes his head. “Two kelp folk swam in from the forests for mating season. And apparently they’re uh,” he pauses, tapping his chin, “How did Hester say it, _attractive enough to make me flare in front of the pups and elders._ ”

Castiel feels heat rise to his cheeks. “Oh.”

“We’re going to take a peek now.” Balthazar glances quickly at Castiel’s abandoned alcove. Castiel pretends not to notice. “Wanna tag along?”

“No, I have to guard my alcove,” Castiel says, even though they both know that is not true. “Thanks anyway.”

Balthazar nods, brushes their fins once more, and swims away with the males. Castiel settles back in front of his alcove and watches them go. 

Strangers are not a common occurrence in the reef, unless you count the clan of sea folk that come around occasionally on their migration of the seas. Castiel is disappointed that the kelp folk swam in during mating season, he would have loved to learn about their culture. 

Dwelling on it for too long will just send Castiel into an even fouler mood, so he swims into his alcove and tidies it up. He has not cleaned it in a few light-darks and it is a good size, so it will take up a good chunk of his time.

As much as he tries to forget them, the kelp folk drift in and out of his thoughts as he brushes away sand and rearranges rocks. 

x

[](http://www.dazzlejunction.com/generators/image-generator.php)  


_A quick sketch of kelp folk!Dean because describing his tail and coloration/camouflage would have been too complicated. It was my first time actually seriously drawing a guy so he looks kind of like a buff girl with stubble, but shhh. Actually, since my scanner's a piece of shit, he looks like a blurry buff girl with stubble. Whatever. It's kind of hard to see, but he does have a second dorsal, and on the front of his tail he has an anal fin and a pair of pelvic fins (hip fins). He's holding his protection charm (in his blurry hand that looks like a blob. Whoops.)_


	2. Splash

**Summary for the Chapter:**

> “Castiel,” Dean whispers, voice so low and wrecked that it sends a shudder trickling down Castiel's spine. “Need you.”

**Notes for the Chapter:**

> Sorry about the short 10 page chapters, guys, they should start getting 15+ now that I've got the plot moving.

Dean wakes before the sky eye. To avoid disturbing the folk in the hollows surrounding him, he sinks to the floor and sets to work quietly cleaning his scales. 

It’s been awhile since he gave them much attention, the arrival of mating season meant he had to stake an obvious claim on his territory before he left so he won’t lose it in the half of the moon cycle he would be away, which left him no time for petty things like maintaining the shine of his scales. In the light-darks before he left, Dean spent whole lights carving border sigils into carefully placed stones. Dean has always been very meticulous about keeping his appearance acceptable, even if the only creatures he encountered that were intelligent enough to appreciate it were occasional pod of dolphins and his own brother, but his territory takes priority over the cleanliness of his scales.

No wonder the pups had been gaping at him, he probably looks like an untamed barbarian. Dean starts to scrub his scales with a clump of seaweed, but he quickly changes his mind and goes for handfuls of sand instead. He doesn’t like to use sand on his scales, the particles can scratch the smooth surface or get caught underneath and itch worse than his mating urge, but seaweed isn’t going to cut it right now. The layer of grime on his tail is as thick as the scales themselves. 

By the time Dean’s scales are back to their regular shine, the sky eye has risen past the surface of the sea and the reef folk are stirring. The gazes of the few that slept in the same alley as Dean linger on him as they leave, but they make no effort to talk to him. He’s not surprised. Outsiders, no matter how peaceful, are things to be wary of. Eventually, all the reef folk make their way to the main path, leaving Dean to himself.

That is, all the reef folk except for small, shy pup hovering behind a column of coral who ducks his head to hide every time Dean glances his way. Normally, Dean would ignore him and be on his way, but he needs the practice if he’s to have his own pup. The last time he talked with a pup was when Sammy still lived in his territory and he’s a little rusty.

“Hey,” he says.

A pair of wide, blue eyes peers out from behind the coral, staring unblinkingly at him in either terror or fascination. Maybe a little bit of both. 

“My name’s Dean.”

More staring. Then, the eyes flick down to Dean’s gleaming tail curiously. 

“Wanna touch?” Dean asks, unfurling his tail from where it’s wrapped around him and rippling his side fins playfully. Like all his folk, he doesn’t like anyone getting too much in his personal space, especially after Gordon, but what harm can a pup do? “It’s okay, I don’t bite.” 

The eyes light up and the pup propels himself out from behind the coral. The orange and green in his tail is still cloudy and broken up by odd patches of undeveloped scales. Sixteen seasons old, Dean guesses. 

“I’m Adam,” the pup says as he gently lays a hand on Dean’s tail. His fingers trail curiously around a large green spot. “I’ve never seen a kelp folk before.”

“Don’t get many visitors, huh?”

Adam shakes his head, blonde hair swirling with the movement. “I saw some sea folk once, though. They were nice. One of the pups was fun to play with.”

“Oh,” Dean says weakly. “That sounds nice.” He struggles for something else to say to keep the conversation moving, but then just gives up and stayed silent. The pup doesn’t seems to mind; he’s perfectly content tracing the camouflage pattern of his tail.

What was Dean thinking? He has no idea how to talk to a pup, let alone _raise_ one. Sam was many seasons old when Dad died, Dean wouldn’t know a newly hatched pup’s fluke from it’s head. If asked, any folk would tell Dean that he will instinctively know what to do when the time comes, but his instincts have been wrong before. Horribly, fatally wrong. Dean suddenly doesn’t trust himself with the reef folk pup and pulls his hands closer to his body, afraid he’ll somehow spoil him through touch.

The main path comes alive with reef folk as the sky eye rises higher, darting to and fro to prepare for another light of mating. Dean starts to worry that the pup was abandoned, or forgotten in the throes of mating passion, but then a male swims slowly around the corner, letting out a sigh of relief when he sees Adam.

“Adamillag,” he snaps. “Get your tail over here right now.”

The pup’s tiny fins snap into his body submissively and he darts over to hide behind the male’s protruding stomach. Dean wiggles his fingers at Adam and the pup goes to wave back, but guiltily lowers his hand when the reef folk that Dean assumes is his father glares at him. Once Adam is safely out of sight behind his greying tail, the folk turns to Dean with a sneer.

“And _who_ are _you_?”

Dean pulls himself up to full height, pleased to see that he’s at least two heads taller than the balding reef folk. “Dean.”

The male huffs. “I don’t suppose you’d be related to that giant nautilus of a kelp folk who stole my alcove? Samuel, or what have you?”

“That’s my brother,” Dean says, bristling. "And his name is _Sam_." His voice doesn’t hold the same pride it does when he usually talks about Sammy. Instead, it’s full of an unspoken challenge. Anyone who has a problem with Sam can take it up with Dean and the sharp end of his dagger. He runs his fingers over the handle of his blade. The familiar feel of the smooth stone grounds him and he pulls a calming breath through his gills. As much as Dean wants to, drawing his dagger would probably get him chased out of the reef. Carrying it into the clan was enough of a risk.

“Well, you tell him to stay away from my Jessickah.,” the reef folk spits. 

Dean’s hip fins flare, though he does manage to keep his back fin from rising in a threat display that even an old reef folk would recognize. “ _Your_ Jess?”

Adam pokes his head around his father’s tail at the mention of the female and the folk pats his head, more forcefully than needed. The pup’s head bobs up and down with the strength behind his father’s hand and he blinks with each pat.

“Adamillag’s mother.”

“Hate to break it to you, but I think she’s chosen another mate this year.” Dean tries to bite his tongue, but his next words slip through his teeth like clever eels. “Why she chose an old whale like you in the first place, I’ll never know.”

The old folk moves faster than Dean could have ever imagined. Between Dean’s last word and his next breath, there are fingertips pressed to his gills. Dean gasps, or at least tries to. Only a small amount of water manages to pass through his gills under the pressure of the male’s fingers and Dean starts to get lightheaded. 

“Careful, minnow,” the folk hisses, a cold, shark-like smile on his pasty lips. “You don’t want to test _me_.”

Dean can think of a few choice words he could toss back, but he stays quiet and still. His pride throbs, but so do his gills and he would rather be insulted than dead. If he really wanted to, Dean has no doubt he could overpower the reef folk, but that was mean exile from the reef and going back to his forest with no pup to show for it. Avenging his ego is not worth losing the chance to mate. He settles for glaring at the male, trying to communicate all the words swirling through his head with his eyes.

“Good choice,” the folk says. He pulls away and reaches out a webbed hand to Adam. “Come on, son. Haven’t I told you not to talk to strangers?”

Dean grinds his jaw as the whale leads Adam out of the alley, but doesn’t give into the urge to take his dagger in his hand and slice the old folk’s back fin. He has more important things to worry about than his reputation.

x

Balancing a smooth, reflective shell on the flat of his tail so he can see what he is doing, Castiel raises his dagger to his face and starts to shave away the hairs that have grown out on his jaw the past few days. He does not press the blade flat to his skin, resulting in a small amount of hair left on his skin that catches on his fingertips when he smooths them over his cheeks and chin. His voice may be ugly, but his outward appearance can still be acceptable.

The reef is whirling with activity around Castiel. Mating songs rise and fall in the background of idle chatter that usually fills the shallows. Young pups chase each other around on the surface of the water, light from the sky eye dancing over their backs, and delight in breaching the water and competing with each other to see who can make the biggest splash upon coming back down. It is a game Castiel looks back on fondly, even though he always lost to the bigger, heavier folk.

An elder named Zachariah swims by, face set in his usual sneer, and Adamillag trails along behind him. The pup looks slightly dazed, though there is a hardly a time he does not anymore. The young folk washed up with a storm many seasons ago and was instantly claimed by Zachariah who, under the foolish notion that he was desirable, announced he would share parenting duties with any young folk who desired it. Castiel vaguely remembers a purple tailed female swimming forward and volunteering, purely for the sake of the pup.

The reef was buzzing with gossip about her bravery and sacrifice for days. Zachariah might have been attractive in his youth, but for as long as Castiel has known him, he has always reminded him vaguely of a sea slug.

Adamillag smiles at Castiel as he swims past and twists his body to corkscrew through the water a playfully, fins wrapping around him like a pup swaddled in kelp.

Zachariah disappears with Adamillag around the bend and Castiel is alone once more. He settles onto the fold of his tail on the sand and holds out his arms in front of him, catching the rippling reflections of the sky eye. They dance across his skin, entwining with each other like the beautiful dance of the sea folk.

The subtle reminder of what is happening makes Castiel scowl again. Thankfully, mating season is only going to last a handful more light-darks, and then he will be free. Being stuck in this small area for so long has made Castiel restless as much as it has soured his mood and he is _itching_ to swim, or at least run through a few exercises. His spear is back at his hollow, though, and there are not any materials nearby that would make an adequate temporary replacement. He could go back to his hollow to get it, but weapons are not traditionally brought to alcoves and Castiel does not need to stand out any more.

A spinefish swims by and Castiel has to propel himself away or risk a rash. He wishes there was something to _do_. At least, something that does not involve disgracing himself further. There are not any materials around him save for common vegetation, which is useless for creating something worthwhile. Weapons require rare teeth or at least stone and the only other thing made from items found on the reef are decorations. 

Even if he knew how to make decorations, there are not any shells that are small enough lying around, though maybe he could use stones or other trinkets stuck in the sand. Castiel tugs on the loop of teeth he is wearing thoughtfully, gauging the sturdiness of the twine they are strung on. Then, he reaches down and runs his fingers through a patch seaweed that’s swaying back and forth with the current.

A piece breaks off in Castiel’s fingers and he huffs. “Too weak.”

Castiel searches for a suitable base until the sky eye is past the highest point and concludes that decoration makers are far more talented than he previously gave them credit for. Even his spear was not as difficult to make as this.

Maybe some stretches will help him keep busy. Castiel’s muscles ache from sleeping curled up in his alcove. It is not that he is not accustomed to sleeping alone, it is that his alcove is so much _bigger_ than his hollow and he feels small and exposed. Curling up seemed logical at the time, a simple way to cure the vulnerable feeling that did not allow his mind to rest, but the groan of his body when he woke said otherwise.

The familiar swish of fins reaches Castiel’s ears, but he ignores it in favor of moving onto a complicated stretch that pulls on the muscles of his lower trail. Whoever it is will recognize him soon enough and leave him in peace. As Castiel completes the stretch and pulls his fluke over his head, he can not help the small grown that escapes his lips; it has been far too long since he stretched these muscles. 

“You don’t sing?”

Surprised, Castiel lets his fluke drop and turns. A male folk is hovering a few lengths away, but he is certainly not a reef folk. His tail is thicker than Castiel’s and splotched with different shades of green and the skin of his torso is far too pale to have spent a lot of time in the shallows. That combined with the fact that Castiel has never seen him before must mean that this is one of the kelp folk Balthazar spoke of.

“I do not,” Castiel replies warily. He pushes himself off the sand and rises to be level with the reef folk. Castiel does not know about this specific one, but reef folk in general tend to be fairly quick tempered, or so he has heard. Putting himself on the same eye level is the first thing a warrior learns to help even the odds in a fight.

“Why not?”

Castiel frowns. He doesn’t remember the _sea_ folk being this nosy about his folk's practices, but then again, sea folk live in clans. Kelp folk live alone. Perhaps the male does not know the difference between rude and curious.

“My voice is not… pleasing.”

The kelp folk regards him thoughtfully, then swims forward and offers his forearm. “Dean.”

Gingerly, Castiel clasps their arms together. Just like the rest of him, the kelp folk’s arm is thick and strong and his large, unwebbed hand wraps completely around Castiel's own lean forearm, but his grip is not overpowering and his eyes are kind. He means no harm. 

Castiel relaxes.

“My name is Castiel.”

x

Dean swam down this alleyway to escape the neverending gushing of that ridiculous male with the snail shells. It was completely by accident that he stumbled upon this male’s alcove. As soon as he saw him, Dean made to turn around and flee to his hollow, but the fact that he wasn’t singing intrigued him. A reef folk without a voice, that’s a curious creature indeed.

“Are you here for mating season?” the reef folk, Castiel, asks when Dean lets go of his arm. 

Dean nods. “There’s no other kelp folk around.”

“I do not think that is true. My friend told me there were two kelp folk here, so there must be another. I am sure you would prefer one of your own kind.”

“Sure, but not if they’re my brother.” Dean smiles, glad that the conversation is settling on something he can talk about. This male doesn't seem as bad as the others. 

Castiel cocks his head. “Your brother?”

“Yeah.” Dean takes his cue and settles onto a coral outcrop near the mouth of Castiel’s alcove. The reef folk watches him suspiciously, like he expects Dean to pull out his dagger and slice him to bits at any second. “Sam. We’re really close. I pretty much raised him after-...” He pauses and glances at Castiel, unsure if he wants to share such personal information, but the reef folk looks politely intrigued, so he gives the short version. “After our mom died.”

“I see.” Castiel remains floating, but he comes an arm’s width closer to the shelf Dean’s on and his eyes flicker down towards Dean’s tail. All the reef folk seem to find him fascinating, like he’s some exotic creature, and Castiel is watching Dean’s side fins with unhidden, if somewhat leery, curiosity. Castiel’s own blue striped tail is void of side fins, which must make maintaining buoyancy hard, and like the rest of the reef folk, he has no spines in his fins. Dean doesn’t see the point of even having fins if you can’t flare them well or use them for sharp turns. 

He’s still frowning at Castiel’s hip fins when he speaks again. “He’s got his own alcove somewhere. Think he’s holed up with some female already.”

“And you do not?”

The question comes out insistent. Dean glances up and finds Castiel staring intently back at him. He suddenly realizes that Castiel probably knows he doesn’t care about his voice. There is a shift in the water between them and Dean cocks an eyebrow, flaring his fins suggestively. 

"Have an alcove, I mean," Castiel clarifies. 

“I was thinking about,” Dean licks his lips, blinks slowly, “carrying this season.”

Castiel swallows and watches the movement of Dean’s tongue hungrily. His back fin twitches and his pupils expand to mask the blue of his eye. 

The itch under Dean’s scales swells like angry storm waves. 

“Is that so?” Castiel asks, voice a notch lower, like the rough scratch of sand scraping over stone.

He’s attractive, Dean has to be honest with himself, and healthy if the muscles flexing beneath his skin are anything to go by. He’s young and strong with all his fins in the right place (even if they are spineless) and his scales are growing in a good pattern. He’s as good a choice as any, if not better. At least he won’t serenade Dean to the point of deafness. 

Besides, Dean’s always liked the color blue. 

There’s very little doubt in Dean’s mind that he and Castiel are thinking the same thing, but he’d rather be safe than sorry. Dean leans back on his elbows and curves his tail down under the shelf, fluke curled submissively, and splays all his fins in a way that he knows looks enticing even to a reef folk. The ripple of his side fins seems to draw the most attention from Castiel, his eyes honing in on the seamless movement with icy blue scrutiny. 

“Any sires you could suggest?” Dean asks, smirking and punctuating his words with a particularly deep side fin ripple.

Castiel’s fins flare bluntly and he closes the last few feet between him and Dean with a snap of his fluke. 

“I believe I do.” 

Castiel spins so quickly that he almost knocks Dean off the shelf, only to return mere heartbeats later carrying a large shell. His hand is surprisingly soft when he grabs Dean’s wrist, calloused only in the places Dean where suspects he holds his spear, and his fingers are pleasantly warm against Dean’s cool skin where he pries his fingers open. Flipping the shell upside down, Castiel deposits a pristine black pearl into Dean’s open palm.

Dean lifts the pearl up and takes his time inspecting it, perfectly aware of Castiel’s insistent gaze on him the entire time. It’s flawless, smooth and clean, and reflects light beautifully. The thing is as big as Dean’s eye; the clam it came from must have been twice the size of Castiel’s head. If Dean wasn’t convinced of Castiel’s strength before, he is now. Breaking open a clam of that size is not an easy task. 

Satisfied, Dean tucks it into the pouch on his belt. When he withdraws his hand, he pulls out a nacre disk and offers it to Castiel.

The reef folk’s fins flare impossibly wider and he accepts the nacre, handling it like it’s his own newly laid egg, and holds out the opposite webbed hand for Dean. The space between Dean’s lungs expands and his gills tingle with anticipation, waves inside of him breaking and calling for what his body craves.

“Come,” Castiel says softly, eye shining. “Come, Dean.”

x

The nacre burns a hole in his hand as Castiel gently pulls Dean, his _mate_ , into his alcove. Dean raises his eyebrows, impressed at the amount of space, and Castiel floats in the entrance while Dean takes a cursory look around. The alcove is pristine, he has had plenty of time to keep it clean and free of sand or stray fish over the last few light-darks, and Dean approves it with a nod.

Next, Dean settles into the seaweed nest, twisting around to test the strength and give of it. Castiel is confident of the nest’s construction, too. He rebuilt the frame twice and filled in the skeleton with all the seaweed he could carry.

When Dean decides all is to his liking, he grins and ripples his strangely shaped fins tease that’s obviously meant to arouse Castiel. 

“Looks good,” he says and removes his belt, laying it carefully on the floor next to the nest. 

Castiel slips the nacre disk into the nook that holds his remaining mating tokens and takes a deep breath. Not only has he attracted a mate, but he’s attracted one of the _kelp folk_ , who- in addition to being notoriously hard to please- are extremely dedicated parents. Castiel’s pup is almost certain to survive, especially if Dean only lays one egg. The thought pleases Castiel in ways that are not restricted to his basic instincts. He senses that Dean has not had the easiest of times. Castiel is glad he can give him something good like this.

Out of the corner of his eye, Castiel watches Dean rearrange his belt on the floor so the dagger holds everything down. Oh, he is beautiful. Different, yes, and strangely patterned, but beautiful all the same. 

This mating will give Balthazar something to gossip about for many seasons to come. 

Despite the fact that Dean has accepted him, Castiel’s heart flutters nervously against his ribcage as he turns towards him. What if he is not enough? What if Dean finds him lacking and leaves before he has caught to find a new, better equipped mate? He is a kelp folk, so he should not care about Castiel’s voice, but Castiel will not pretend to know how kelp folk think. Nothing is stopping Dean from leaving and with his ethereal beauty, he would not have any trouble replacing him.

Castiel smooths his trembling hip fins with unsteady hands. No, he cannot think about this, not in such a sacred place. An alcove is a place of joy and good, a place where _life_ is created. He will not let himself spoil that with his negative thoughts. 

In a burst of courage, Castiel swims up behind Dean and runs a hand slowly across his shoulder and down his arm, waiting for a reaction. Dean breathes deeply and stills under Castiel’s touch, which Castiel takes as an invitation to lean forward and nose at the back of his neck. 

Dean shudders. 

The play of muscles in Dean’s shoulders and back is entrancing, the tiny dots on his skin there seem to come alive with every movement. The mouth of the alcove is the only source of light and each tiny tremor that shivers through Dean throws new, sharp shadows across his body. Castiel thinks that in the entire population of kelp folk, there cannot be a single one as perfectly sculpted as his mate. 

Dean is strangely cool, like a rock that has been sitting in the shade of the coral. Little bumps erupt in the wake of Castiel’s hand and Dean shivers whenever Castiel skims his warm fingertips ever so lightly across his gills. To caress him there is thrilling, knowing that with one quick and clever press, Dean would be dead, and yet he already trusts Castiel enough to not jerk away from his touch to such a vulnerable part of his body.

Countless breaths pass as Castiel runs his fingers over the smooth flesh of Dean’s back and arms. He discovers that Dean especially likes the spines of his backfin touched. He arches into the contact and flexes his fins while drawing quick, sharp breath whenever Castiel rubs his fingers over them. He stores that fact for later. 

Even though he knows he should not, Castiel cannot help but press a chaste kiss under Dean’s ear fin every time his breathing stutters. It is not his place, kisses are reserved for true mates, but he is willing to risk it for the chance to taste Dean’s skin. He tastes like the ocean, obviously, but there is something darker underneath the salt and the water and the sky eye’s light that Castiel wishes he could chase. It reminds him of how the above feels on his tongue after a light storm.

Before long, the muscles of Castiel’s sheath have tightened and he is struggling to keep them from contracting. Gradually, Castiel lets his hands slip lower and lower, sliding over Dean’s waist and looping around to feel along the place where skin meets scale. Dean lets out a soft gasp when Castiel drops one of his hands to brush against his slit. He is pleased to find that Dean is just as excited as he is, and presses against his bulging sheath, groaning in response to Dean’s startled moan at the pressure. 

“Castiel,” Dean whispers, voice so low and wrecked that it sends a shudder trickling down Castiel's spine. “Need you.”

x

  
[](http://www.dazzlejunction.com/generators/image-generator.php)

_Yo here's Cas staring pensively off into the distance cause his tail would have been even harder to describe than Dean's. I think I'll post at least one new character illustration with each chapter because everyone likes art no matter how amateur it is._

_Anyway, you can see how Cas is more lean than Dean is. He's built for open water living so everything about him is all for speed and agility while Dean is stealth and strength. Also Cas' fins are completely opaque where Dean's are translucent. I talked a lot about the spines in this chapter and how Cas doesn't have them. Cas' fins are more like what you would imagine a beta fish's to be like- flowy is really the best word to describe them. He can move them, for displays and emotional expressions and stuff, and he doesn't have the same control over them as Dean. Precise fin usage is crucial for kelp folk camouflage and it makes their displays about 300x more effective than reef folk's._

_I went a little crazy the other day and compiled a huge list of what everyone's tails look like, so if you have a burning desire to know what someone looks like before I draw them shoot me a message on tumblr_

**Notes for the Chapter:**

> This chapter may or may not be dedicated to Splash
> 
> again, here's the glossary link if you need it ---> http://celestial-sexhair.tumblr.com/post/86242454950/riptide-glossary


	3. Whirlpool

**Summary for the Chapter:**

> Castiel’s hands are _burning_. They sear Dean’s skin when they press into him and make heat ripple through his body. The itch under his scales turns into an urgent throb, strengthening with each heartbeat.

**Notes for the Chapter:**

> Added some new tags for this, so please read them. It got kind of angsty? This was supposed to be plotty porn, I don't really know what happened. Oops?

Castiel’s hands are _burning_.

They sear Dean’s skin when they press into him and make heat ripple through his body. The itch under his scales turns into an urgent throb, strengthening with each heartbeat. 

Dean has never felt this way before, not even when he touches himself. Castiel’s touch seems a hundred fold more powerful than his own. His fingers are soft and warm where Dean’s are rough and cool and nothing can compare to when he smooths over Dean’s back spines. 

Then, Castiel’s fingers slip down his body and slide over his sheath and for a heartbeat, all he sees is white, bright and burning like the sky eye. Dean’s back arches so far he thinks it’s going to snap and he whimpers with the throb that squeezes along his body, making his very bones vibrate with want. And oh, holy sea, does he _want_. He’s still teetering between unsure and confident, too hung up on being in unfamiliar territory, but he trusts Castiel and his own biology to guide him. He’s done listening to the voice of his father and the sound of Gordon laughing as he holds a dagger to Sam’s throat.

Something clicks inside him and, finally, he admits it. Dean is lonely. He is. There's no use denying it. There's no shadow looming over him, picking apart his every weakness like it's his death sentence. No _Protect your brother, Dean_ or _Emotion is vulnerable, Dean_ or _Get ahold of yourself, Dean. Be mature _. John is dead and Dean wants a pup.__

Now, his life is in _his_ hands. 

“Castiel,” Dean breaths. He squeezes his eyes shut and silences the nagging presence in the back of his head telling him he's not good enough, was never good enough, will never _be_ good enough and says, “Need you.”

Castiel makes a deep humming sound in the back of his throat and digs his fingers into Dean’s scales, massaging his sheath. Dean cries out at the bolt of heat that shoots through him and erases any last doubts. Dean grapples for purchase on the wall in front of him, but the rock is smooth and he can’t find anything to grip, so he reaches backwards and settles for Castiel’s shoulder instead. The throb curls up his spine and fans out across his whole body, reaching all the way to the tip of his tongue and settling in the ends of his fins.

With a single finger, Castiel traces the slit of his sheath, gently rubbing the engorged flesh. Dean has to bite his lip to keep quiet and squeezes Castiel’s shoulder so hard he’s sure it will be bruised in the morning. He bucks into the pressure and one finger becomes two, a solid presence against him asking for entry.

A handful of breaths later, Castiel’s fingers become more insistent and he lets out an almost silent huff at the lack of response to his efforts. Dean knows what Castiel is doing- or at least _trying_ to do- but somehow, he can’t give it. Despite what he wants, what his body is asking for, Dean is still nervous. Unsure anxiety is keeping him from letting go of his last inhibitions. He knows he shouldn’t feel like this, Castiel is his _mate_ after all, yet no matter how hard he tries, Dean’s waves won’t come crashing down.

To his credit, Castiel is patient. An endless amount of breaths pass across Dean’s gills as Castiel steadily adds one finger then another to the two already pressing on Dean’s slit. His own sheath bulges against Dean’s rear and he grinds back against it, trying to reciprocate the attention Castiel is giving him. It’s inadequate compared to the pleasure Dean feels, he knows, but at least it’s something.

After what feels like a whole season, all four of Castiel’s fingers are teasing Dean’s slit, but they still don’t dip in. Dean grits his teeth and squeezes his eyes shut, clenching the fist not on Castiel’s shoulder so hard it aches. He’s hovering somewhere between brutal pleasure and the pain of oversensitization, rapidly approaching the latter. 

He wants to give in to the storm inside him, it’s essential to this mating that he does, but apparently the resolve he set all those years ago to never let anyone get close to him applies physically, too. The wall he built to do that is very old, almost as old as Dean himself, and it’s going to take more than a few touches to crack it, let alone wear it away.

“Dean,” Castiel says. “Relax.” He leans down and runs his tongue across Dean’s gills. “Let me in.”

“I _can’t_ ,” he says, strained. To his horror, he feels his eyes start to sting and his throat swell, but he can’t do anything to stop it. _Never good enough. Can't even do this one simple thing right, Dean. Worthless._ “I’m sorry, I’m sorry. I can’t.”

Dean tries to twist away from Castiel’s burning grip, but his arms have locked and Dean is trapped. He should let him flee, he’s useless to Castiel if he can’t breed him, but the arm just gets tighter and tighter the more Dean struggles. 

Suddenly, Dean is spun around and slammed up against the wall. Dean gasps sharply at the sight Castiel’s face- pupils blown, fins flared, skin flushed. The fingers return to his slit, only this time, Castiel is locking Dean with his piercing stare.

“You can,” Castiel insists. “And you will.”

Dean stills, trapped by both Castiel’s hands and eyes. It’s even worse face to face. It’s as if Castiel can read everything Dean is thinking, see how broken he is in his skin and in his gaze. 

When he tries to turn his face away, close his eyes, Castiel uses the hand previously holding Dean to the wall and grasp his chin and turn his face back towards him.

“No,” Castiel says. “You will look at me.”

Castiel’s voice is firm and Dean shudders at the sound of it. He has no choice but to obey. It’s embarrassing, holding Castiel’s gaze when he knows he will disappoint his mate, but he won’t turn away. He won’t show weakness.

Castiel’s gaze narrows and he frowns when Dean still doesn’t give way. Tipping his head, Castiel lets his eyes fall to where his fingers are try to work Dean open. Dean squirms under the scrutiny, fins rippling uncomfortably, and then Castiel is pulling his tail under himself and settling on the fold of it before Dean.

“Castiel?...”

Dean loses his grip on Castiel’s shoulder. Now Castiel is eye level with his stubborn slit, studying him like he’s a puzzle. Dean blushes, embarrassed by the the scientific contemplation. It's bad enough he's not comfortable enough in his own scales without someone studying him. 

Burying his hand in Castiel’s hair, Dean tries to pull him away, but then Castiel sticks out his tongue and flicks it over Dean’s slit.

x

Castiel frowns.

He is sure Dean should be opening to him by now., but tissue under Castiel’s fingers remains firm and unyielding, not giving even when Castiel presses and massages. 

Dean looks equal parts embarrassed and aroused, simultaneously pushing into Castiel’s fingers and trying to squirm away, but the pleasure melts into pure embarrassment when Castiel glances down at where he is touching him. His slit is red and swollen, pushing apart the scales of his tail to expose himself, but there is still no dilation.

Castiel has no fingers left, but thanks to Balthazar’s bragging, he knows of other ways to prepare one's mate. Castiel used to think Balthazar’s comments were annoying and brash, but now he is grateful that he knows how many ways there is to wring pleasure from a body. He lowers himself to the floor of the cave, ignoring Dean when he says his name like it is a question, and tries to think of the best direction to approach this from.

When no clear answer comes to mind, Castiel simply leans forward against the will of Dean’s hands in his hair and licks up Dean’s slit like he would clean bits of food from his fingers, tasting salt and the cool waters of the kelp forests.

It must work because Dean stops trying to resist Castiel and instead pulls him closer with a moan that sounds like it was startled out of him. Castiel’s lips stretch into a small smile and he grasps Dean’s tail to hold him in place then does it again, slower. Dean writhes under Castiel and tosses his head back, a deep flush working its way down his neck and chest. A thrill runs down Castiel's back at the desperate sound his mate makes. 

A tongue is more agile than fingers and Castiel has soon managed to dip his tongue into Dean’s slit. He lets out a triumphant noise, smiling around the muscle, and Dean shudders and flexes his fins.

“Cas,” he pants. “Holy sea, Cas, do that again.”

Castiel looks up questioningly at Dean, but hums again, and again Dean shudders. His slit is twitching, jumping with every tiny movement of Castiel’s tongue, and humming makes Dean shake against him. Tugging on Castiel’s hair, this time in encouragement, Dean breathlessly asks for more. 

Castiel hums, long and low, and abruptly Dean’s slit opens and Castiel’s tongue slips inside. Dean feels it, too, and he makes a sound somewhere between a whimper and a groan. Castiel replaces his tongue with two fingers, gently stretching Dean and working him open. 

Castiel’s own sheath is pounding insistently and he rubs it with his free hand to relieve the ache. His instincts demand that he take Dean now, but Castiel does not wish to hurt him. A previously mated male would not have to be stretched, but by Dean’s reaction to Castiel’s fingers he would guess he has never been bred. Castiel would rather take some time to be sure he is ready than accidentally hurt his mate. 

While he adds another finger, Castiel traces along the smooth outline of Dean’s scales with his tongue. It aches from working him open, but the appreciative sigh Dean lets out makes it worth it. Castiel would imagine this part of the mating would be strange, if not uncomfortable, and the soothing touch will distract Dean from that. 

The tip of Castiel’s third finger brushes against something hard compared to the soft wall of Dean’s slit and Dean jolts, convulsing around Castiel’s fingers. Castiel’s eyebrows rise. He was not aware Dean’s erection was so close to unsheathing. Perhaps his fingers do not feel as uncomfortable as he thought.

Dean’s fingers run through Castiel’s hair, then stroke down his face. He grips Castiel’s chin when he reaches it and gently pulls under Castiel rises up off the floor to meet his gaze.

“I’m ready,” he says and glances down at Castiel’s slit with something that would have been a leer if his eyes were not so hooded. Instead, he just looks eager. “Your turn.”

Castiel cocks an eyebrow and Dean’s tone playful, almost mocking, tone. “Would you like to help?”

Smirking, Dean says, “My pleasure.”

Castiel closes his eyes at the first touch to his sheath. Dean’s actions are hesitant at first, furthering Castiel’s conclusion that he has never mated with a male, but his fingers grow surer with every heartbeat. All of Dean’s fins are flaring impatiently and he rubs their hip fins together, shocking Castiel out of his concentration with the zap of pleasure it creates. His fins are very sensitive when he’s aroused. 

Dean pets down Castiel’s back with his unoccupied hand, stopping when he reaches his back fin and tickling the place where membrane meets skin. The electricity of Dean’s rough fingers against that place makes Castiel shiver and flex his fin into the sensation. 

A familiar feeling engulfs Castiel, tingling the back of his neck and gills. It is elusive, dancing around the edges of his consciousness and like always, he he has to concentrate to hold onto it. Castiel grabs at it, pulling it towards him, then takes a deep breath and lets it wash over him.

Finally, Castiel’s sheath relaxes and his erection slides free into Dean’s hand. The explosion of pleasure under his scales at the feel of Dean’s fingers on his penis is expected, but Castiel doesn’t expect the _intensity_ of it. He gasps and thrusts forward, the head of his penis bumping against Dean’s tail. Both his hand and his tail are cool, a delightful change from the soft warmth of his own hand.

“Eager,” Dean says, but the confidence in his voice sounds thin. Castiel closes his hand loosely around Dean's wrist in concern as he clears his throat and gives Castiel’s penis a few loose strokes, leaving Castiel aching for more. “I just wanted to say, uh, before we start-...” He thumbs across the tip of Castiel’s penis nervously, clears his throat again. “Y’know, I’d really appreciate if, um... It’s my first time….”

Castiel rescues Dean from saying the words he is obviously having trouble getting out and says, “I understand, Dean.”

Dean smiles in relief. “Yeah.”

“I will be gentle,” Castiel says as he wraps their tails together. Dean presses his fluke hesitantly against the top of Castiel’s tail. His tail is too short to reach Castiel’s fluke. “I will take care of you, Dean. Do not worry.”

“Right,” Dean says, but he still does not sound convinced.

x

This is going to hurt.

It’s the first thing Dean thinks when he sees Castiel’s dick. From a logical perspective, Dean knew it would be about the same size as his own, but he was hoping he was larger than average. The only time he ever saw another folk’s dick was by accident when Sammy was discovering the perks of puberty. But he’s effectively scrubbed that image from his memory.

Apparently, either Dean is average or Castiel is big too, because the erection prodding his scales is just as large as his, if not bigger. It had been a struggle just getting the fingers in him, and though it did feel good in a strange way once he was stretched, Castiel’s dick is bigger than all his fingers put together at the base. And _round_. Fingers only forced him to stretch one way.

Castiel wraps his tail more firmly around Dean’s for leverage and grasps his erection at the base, starting to push on Dean’s slit. As the blunt head starts to part the folds of tissue, Dean grabs at Castiel’s upper arms and clings onto him. He takes deep breaths and forces his fins to lay flat against his body in a submissive, if neutral, position. He knows Castiel will stop if he reads Dean’s discomfort in his display and he’d rather be in pain than alone.

The second Dean’s slit gives way, Castiel slides in without any resistance and Dean loses the ability to breathe. In his entire life, he’s never felt this full, like he’s swallowed half the sea and is going to burst around the edges. Castiel groans and turns his face into Dean’s neck, nosing along his gills. The touch sparks a kind of dangerous pleasure that zips along his spine, but it’s lost in flood of fullness Castiel leaves him with. 

Dean only has a few heartbeats to adjust before Castiel starts to rock into him with slow, shallow thrusts. A sound embarrassingly close to a squawk falls from Dean’s lips. It feels so _strange_ , nothing like the one or two fingers he experimented with during his maturing or Castiel’s efforts to open him up. Dean doesn’t know how some males come to enjoy this, he doesn’t think he’ll ever get past the weird sensation of having a space inside him carved out like this.

Castiel’s hands start to wander, skimming across Dean’s chest and stroking down his sides until he finds his side fins. Dean winces when Castiel rubs his spines. It feels good- amazing actually- but the heated pleasure it creates is just too awkward combined with the stretch Castiel’s dick. He rips his fin away and grabs Castiel’s hands, guiding them to his hips instead. Castiel holds onto him without hesitation, using his hipbones to drag Dean into each of his thrusts. 

With each deep breath, Castiel’s gills flutter against Dean’s and the water rushing out of them spills across his neck. Every stroke into Dean’s body leaves Castiel panting like a winded elder, mouth falling open so he can get enough water flowing across his gills. 

Dean feels the same, but for a completely different reason. It takes effort not to grunt in discomfort or push Castiel away. He closes his eyes and thinks about the outcome, not that this will have to happen mulitple times to ensure he catches. His body is rebelling enough for him- he can feel his walls squeezing around Castiel’s dick, fighting the intrusion. By the way Castiel groans with each particularly strong contraction, he either doesn’t know or doesn’t care what they mean. 

Dean’s arousal fades, erection retreating back into his sheath and slit narrowing. Castiel gasps at the tightness and noses under Dean’s chin, sucking the skin he finds there between his lips and nibbling on it. It will bring a mark to the surface, Dean knows, and he shivers. Every folk that sees it will know what’s happened between them and it makes something uncharacteristically possessive curl at the base of Dean’s spine. Castiel is Dean’s mate. That connects them on a base level and, despite the ache of Castiel’s dick cutting into him, Dean wants to hold him close and never let him leave. 

“Dean,” Castiel moans, squeezing his hands where they're grabbing at Dean’s waist. His erection swells inside Dean, splitting him open farther. 

Finally, he is close.

x

Castiel gasps as Dean’s channel tightens around him, squeezing more of the liquid heat into his veins. Outside, Dean may be cool, but inside he is hotter than Castiel himself. The effect sends shivers cascading down Castiel’s body and ricocheting back up into his groin.

From this position, Castiel is level with Dean’s neck and he can not help but seal his lips over the hard line down the middle and draw some skin between his teeth, gently working it to pull a bruise to the surface. If, for some reason, Dean was to leave the alcove, there would be no doubt as to what transpired between them. When Castiel lets go and sees the result, a dark red mark blooming over Dean’s throat, he has to bite the inside of his cheek to keep from climaxing.

Another sharp squeeze of Dean’s channel punches a moan that sounds like Dean’s name out of him. His penis fills with blood and throbs in the way that means he is close to his climax. He wants to bring Dean there with him- see his face and hold him as he shudders though it- but every time he goes to touch his mate’s fins or slit, Dean always jerks away and moves Castiel’s hands somewhere else. 

Castiel’s capacity for thinking is fast being erased by the urge to chase his climax. As he falls into that abyss, the need to see and feel Dean come apart under his hands fades and is replaced by a biological urge to breed his mate. He digs his fingers into Dean’s already bruised hips and bites his shoulder, thrusting in deep one last time before he climaxes. 

It comes with a buzz under his scales and a shudder over his skin, trickling into places Castiel did not even know he could feel. Threads of heat weave through his veins, twisting and twining around each other, weaving into every crevice between his scales and folds of his skin. The mating itself was like a ripple compared to this. This is a violent whirlpool, sucking him down into the blackness and radiating pleasure that blooms through his body.

It rages on for far too long and yet not long enough, then it is over. Gradually, it trickles away, leaving Castiel feeling empty and spent. He realizes he is still clutching Dean’s waist and lets go, petting down his sides instead and letting his head fall to his shoulder. 

Dean’s gills flutter rapidly against his cheek.

Castiel frowns and turns his nose into Dean’s gills. His own breaths are deep and slow, but Dean’s are fast and come in quick succession of each other. He feels taut under Castiel’s fingers, not sated and relaxed like he should be. Like Castiel is.

“Dean?” Castiel lifts his head off Dean’s shoulder to look him in the eye. He untwists their tails and carefully withdraws his erection from Dean, not missing the wince from his mate when it slips out. Already, he is sliding back into his sheath, but if Dean requires more stimulation Castiel will find a way to provide it, as tired as he is.

Dean slumps against the wall and smiles, but it comes out more like a grimace. “I’m good, Cas.”

Castiel’s frown deepens. Even through the haze of his climax, Castiel knows what “good” sounds like, and that is not it. Dean sounds… distressed. Anxious. 

Perhaps he is too embarrassed to ask, or he thinks he will wound Castiel’s pride. Castiel almost snorts at the thought. He had no pride to begin with and considers himself lucky to even have a mate. His sexual prowess is no matter to him as long as Dean is pleased, too. 

“Are you certain? I can-”

“No!” Dean bats Castiel’s hand away when he reaches for his slit. After a heartbeat of wide, panicked eyes, he relaxes and clears his throat, smiling again. “I mean, I’m overstimulated.” He covers himself with his hands in false modesty, wearing the same cocky grin the entire time. “Just wanna sleep.”

“Alright,” Castiel says, then holds out his hand for Dean to take and leads him to the nest.

x

Dean is strangely empty now, where only heartbeats ago his body was complaining about being too full. It makes him irritated, to want something and not want it at the same time.

His slit and throbbing and pulsing a dull pain that makes each beat of Dean’s tail seem awkward and stiff as Castiel leads him to the nest. He’s glad he has a whole dark to recuperate before they mate again. If he had found a male kelp folk, there would be no stopping for many light-darks until they were both too exhausted to carry on. A ghost ache shudders through his abdomen at the imagined situation. 

Castiel is lethargic and sleepy when he curls around Dean in the nest, and as soon as he is comfortable his breaths even out and he drops into sleep. Dean wishes it was that easy, but he is too on edge to sleep. He’s like a shark who can smell blood- jittery and twitchy and unable to settle down.

Dean briefly considers arousing himself again and stroking himself to completion just to fall asleep, but quickly puts that thought from his mind. Not only is he too anxious and uncomfortable to arouse himself, let alone masturbate, but he would probably wake up Castiel and that would undoubtedly lead to more mating.

The ache is already fading, lessening with each thump of Castiel's heart against Dean's back, and by the next light Dean thinks he will feel somewhat normal again. As long as he doesn't bleed, he can pretend. He's suffered through sharp-tooth bites and dagger wounds, he can endure a few light-darks of the strangeness of being mated. 

He burrows back into Castiel’s warmth and wraps Castiel's arm, thrown loosely across him, tighter around his chest. At least the nest is soft and cushiony and he can be comfortable as he waits for sleep to come. 

For many breaths, Dean waits. It’s not until the sky eye has long since sunk into its ocean bed and the sky pearl has taken its place, shining silver light down into the waters of the reef, that he finally drifts off.

**Notes for the Chapter:**

> Thanks for all the lovely comments, guys! It makes my day to read them ^^
> 
> (note: I was going to add Anael to this chapter, but I still haven't colored her and I wanted to get this chapter up since it's been, like, a week since the last update. I might go back and add her or I might just add her to the next chapter.)


	4. White Water

**Summary for the Chapter:**

> “Dean, do you trust me?”
> 
> Dean blinks. The mood takes a steep dive from flirty to formal. “What?”
> 
> “Do you _trust_ me?”
> 
> “Um.” Dean swallows. Inexplicably, he does. Not completely, and not as much as Sammy, but he’s already damaged goods in that category. This is as good as it gets. “Yeah, I guess so.”

It is an ear fin to his face that wakes Castiel.

He flails, blindly reaching for his spear before he remembers that he is not in his hollow. In the midst of his short panic, he almost smacks Dean, who has turned towards him sometime during the night, in the face. Dean stirs and grumbles sleepily, but settles back into the nest when Castiel calms. His fins are relaxed and swaying with the gentle current from Castiel’s gills again in just a few heartbeats.

As to not wake Dean, Castiel eases himself ever so gently from the nest, lifting his arm from where it is wrapped around Dean’s back. He looks too peaceful to wake and they will need all the sleep they can get in the next few light-darks. Already, there is a need is building in his sheath.

A rumble from his stomach reminds Castiel that there is a different kind of need building, too. The only downside to his alcove is that it is the farthest it can possibly be from the food storages. Technically, the supply is reserved for when food is scarce, but the folk that see mating males stealing from it always look the other way. 

If he really wanted to, Castiel could swim from the food storage and back and hope Dean did not wake before then, but he would prefer to be back as soon as possible. The clam bed is just a few short lengths away and clams provide just as much energy as the food in the supply, even if they will have to take the time to crack them open first. Castiel can swim to the beds and back much quicker than if he swam all the way across the reef to the storages. 

The sea outside the alcove is bright when Castiel swims out and he has to blink rapidly to adjust his eyes to the light. Once the spots dancing in his vision are gone, he swims up and over the alcove towards the clam bed. It is just on the other side of the coral, he can already see it.

The few fish that are browsing among the clams scatter at the sight of Castiel. A handful of seastars dot the grey expanse of shells, but other than that, the bed is lifeless. On a normal light, this bed would be swarming with folk teaching their young pups how to crack shells or adolescents competing against each other to see who can find the most pearls. The stillness is almost eerie.

However, it does mean that Castiel gets his pick of the clams. He glides along the bed, plucking the biggest clams off the floor. He considers grabbing a seastar to decorate himself with- it would contrast nicely with his dark hair and blue scales- but bypasses it upon reminding himself that he no longer needs decorations to impress Dean.

There is a small nook under a protruding rock that seems to have been skimmed over by the bed’s other visitors and Castiel collects a fair amount of clams there. He only chooses the ones that are heavy and hard to detach from the rock’s surface, ones full of good meat. 

Another folk swims over the reef into the bed and Castiel glances up. Even from this distance, he recognizes the purple and green tail within a heartbeat. Castiel groans. Balthazar.

It is too late to flee now. Balthazar is swimming towards him faster than a sharp-tooth on the hunt. He is on one of his gossip missions, that much is clear by the way his ear fins are flapping like a playful pup’s. Castiel shakes his head and turns back to searching the floor for large clams.

“Cassie!” Balthazar grins as he approaches Castiel. He reaches forward to clap Castiel on the shoulder, then scrunches his nose and pulls back sharply. “Cassie. You _reek_ of sex.”

Castiel sighs. “What do you want, Balthazar?” No point in delaying the inevitable. 

The male’s smirk returns and he folds his arms across the rock Castiel was previously hunting under. “Heard you landed one of the kelp folk.”

“You heard correctly.” He plucks another clam and adds it to the growing pile in his arms. 

Balthazar chuckles and wiggles his eyebrows. “You old dolphin. Betcha gave him the mating of his life.”

His sentence trails off in a way that is obviously meant to entice Castiel into sharing the details. It is customary for males to brag of their skills in such areas, the sea knows Castiel has heard his fair share of mating stories in his lifetime, but he has no desire to share what happened with Dean. It is not that he is ashamed or embarrassed, he simply thinks those kinds of things should stay in the privacy of an alcove. 

“I suppose,” he says vaguely. 

Maybe if he just avoids directly answering Balthazar’s questions, he will go amuse himself elsewhere. Castiel enjoys Balthazar’s company, but sometimes he can be a little… overzealous. Right now, Castiel is not in the mood to put up with his behavior. He just wants to get back to his alcove and share the clams with Dean without someone trying to wring information from him.

“You suppose?” Balthazar repeats flipping on his back and folding his arms under his head. “That doesn’t sound very confident.”

“He was very quiet.” Castiel shoots a look at Balthazar. “Not everyone feels the urge to scream their pleasures to the above. Unlike _some_ folk I know.”

“Everyone _I’ve_ known feels the need,” Balthazar says, somewhat snidely, then smirks teasingly and says, “Guess you’re just not as _pleasurable_ as me, Cassie.”

Castiel scowls but doesn’t answer as he shifts the clams in his arms so he can pick up one more. This should be enough. If not, he can just come back when the bed is mercifully Balthazarless and hunt for more in private.

Unfortunately, as he turns to leave, Balthazar grabs his at his fluke. Castiel looks back, frown deepening, and jerks his fluke out of Balthazar’s hand. Tired of games, he almost swims away, but the serious look on his face gives Castiel pause.

“You _did_ pleasure him, right, Cassie?” Balthazar asks.

“Yes,” Castiel snaps immediately. Then upon reconsideration, he says haltingly, “Though I do not believe he...finished.”

Balthazar sighs and covers his eyes with his hands.

“I offered!” Castiel says defensively. “He rejected my advances.”

“Cassie,” Balthazar says, shaking his head. “Cassie, Cassie, Cassie. Put those down, it’s time we had a little chat.”

x

Castiel isn’t there when Dean rises from his sleep. When he realizes he’s curled up alone in the nest, fluke spread out over where Castiel had been when he fell asleep, he almosts panics. After falling asleep with Castiel by his side, waking up alone is distressing to say the least. But it’s still early. The sky eye hasn’t even completely risen from the ocean. Castiel probably left to relieve himself or get some food or something.

Dean stretches, groaning as his tail pops. He’s not used to sleeping with another folk, the last time he shared a nest with someone was when he and Sam curled up next to each other at night for security. And Sam hadn’t wrapped around him like an octopus as Castiel seems fond of doing.

Dean pushes himself out of the nest and swims lazily out of the alcove, squinting in the early light of the sky eye, and lets himself sink to the floor. There’s a patch a seaweed just outside the alcove that offers protection from prying eyes so Dean can relieve himself. After, he fills in the rest of the hole with sand to cover the waste and goes back inside the alcove. He’s still tired and Castiel’s not back yet, there’s no reason he can’t go back to sleep. 

The next time Dean opens his eyes, Castiel is sitting on the edge of the nest scrubbing his scales with a knotted rope of kelp. Dean watches him for some breaths, grudgingly admiring the fluid movement of his fins, before speaking.

“Hey,” he says, voice rough.

Castiel turns and offers Dean a tight smile, putting the kelp aside. He looks nervous, which is foolish considering what they did last dark. Nothing can be more intimate than that. “Hello, Dean. Did you sleep well?”

“Yeah.” Dean sits up and rubs the sleep from his eyes. “Where’d y’go?”

“To get some food.” Castiel leans back to show Dean an impressive pile of clams sitting on the alcove floor. “I hope you like clams?”

Instead of answering, Dean grins and lazily slides out of the nest to grab one. He takes his dagger from where it’s sitting on top of the nest on his belt and carefully works it between the two halves of the shell, then twists it to pry the clam open. Castiel watches with a faintly amused expression as Dean noisily slurps the clam from the shell and swallows it whole. 

The few clams he can find in the forest are small and bland, and even then he considers them a treat. Charlie has told him countless times how rough and unappetizing his clams are when she passes through on her biseason visit to the reef with Gilda. In fact, she swore up and down that if he ever visited the reef with her, she would make him try the clams.

They don’t disappoint. Dean cracks open another one and swallows it down just as easily. They’re fatty and plump but not slimy and the texture, so unlike the chewy ones he digs up in the forest, is smooth.

Castiel’s smile grows and Dean thinks if he smiled any wider, his nose would crinkle. “I’ll take that as a yes, then.”

They eat in a silence that’s only broken by the occasional muffled slurp or crack of a particularly stubborn shell against rock. Castiel’s brow is furrowed like he’s in deep thought and every so often, he’ll frown seriously. It makes Dean’s blissful early mood wash away, leaving him just as antsy and tense as the night before. By the time the pile of clams is reduced to a collection of empty shells, Dean’s ear fins are periodically flexing and flaring uncomfortably. 

Dean turns from Castiel and puts his dagger back over his belt, which has already drifted a few lengths in the sway of the tide. He can feel Castiel’s eyes boring into the back of his neck as he tucks his belt against the side of the nest and he knows what’s coming, so it’s no surprise when Castiel’s hand appears on his waist, fingers gentle and soft.

Dean closes his eyes as Castiel starts to stroke his hip, almost tickling as they glide from skin to scale. He doesn’t press himself to Dean’s back like last night, it’s only his hand at touches Dean. 

“It is customary,” he says finally, softly. “To remove your mate’s decorations after the first night.”

Dean glances at his belt and dagger. Oops.

Castiel’s hand disappears and he swims around Dean, hovering unsurly next to him. “I was wondering…” He pauses, tugging on the string of teeth around his neck. “You would indulge me?”

The look on Castiel’s face is one reminiscent of Sam’s pup days and it’s one he can’t refuse, even if it’s on a grown man’s face. The dolphin calf eyes are almost more irresistible on Castiel than when Sammy flashes them.

Dean nods. “Sure.”

The soft smile returns and Castiel reaches for Dean’s necklace, but Dean leans away and shakes his head, fingers closing around the shark tooth dangling from the end. 

“Not this,” he says. He’s worn it so long that he feels too exposed without it. Plus, it serves as a constant reminder of what’s happened and what can never happen again. “This stays.”

Castiel nods, then bows his head so Dean can pull the teeth from his neck. Once that’s off, Dean moves onto the small pink shell dangling from the end of the single braid in Castiel’s hair, unwinding the strands from around it and running his fingers through the lock of hair until the plait is gone.

“Why so few?” Dean asks as he moves onto the final decoration- a long rope strung with bits of multi-colored coral wrapped around his upper arm. 

Castiel lifts his arm from his body so Dean can reach the knot under it. “Braids or decorations?”

“Both.”

Castiel shrugs, a one-shouldered thing that’s only a little bit adorable. “Too many are cumbersome and uncomfortable.”

Dean huffs in agreement, remembering thinking the exact same thing when he first saw the reef folk. “The rest of your folk don’t seem to mind.”

“I have never been like the “rest of my folk.”’ Castiel’s hands come up and make a vague, wiggly gesture at the end of the sentence, like he’s trying to describe the entirety of his folk with one movement. “I believe I am what you would call a disgrace.”

Dean bites his lip. “I know what you mean.” He finally unties the knot in the coral rope and unwinds it from Castiel’s arm. It leaves an imprint when he pulls it away.

Castiel locks him with a curious look, head tilting to one side like he doesn’t believe him. If a hundred bad memories weren’t flashing through Dean’s mind, he might puff out his chest at the indirect compliment. “You?”

“I guess.” Dean looks down, wrapping and rewrapping the coral rope around his hand so he doesn’t have to look into Castiel’s eyes. “Y’know, never mated. And, uh-” he stops abruptly, glances up at Castiel. “Yeah. That.”

Castiel chuckles, but he doesn’t sound amused. “I am afraid I outrank you then, Dean.”

Tipping his head up, Dean asks, “Yeah?”

Castiel does that shrug again and takes the rope from Dean. “I never much fit in no matter what I did. I have always been... out of place.” His lips turns down slightly as he collects the rest of his decorations and slips them into a little nook in the wall. “I have never minded until this mating season. It was more lonely than I had anticipated.”

Dean hums in a way he hopes is consoling. What do you say to that? He’s never been good at the whole heart to heart thing, even with Sammy. It makes his chest feel like a squid is squeezing the breath out of him. 

Castiel swims back over and slides his hands over Dean’s hips again. Dean shivers.

“Until you came along, of course.”

Heat blooms in Dean’s cheeks and he mumbles, “Shut up.”

Castiel leans forward until their noses touch, eyes shining with a secret smile. “It is true, Dean. You and I are the talk of the reef. All the males are very envious of me. All the females, too, for that matter.”

Dean shoves good naturedly at Castiel’s chest and pretends to gag. “Ugh. We’re mates, not _true_ mates. Romance isn’t on the list of requirements.”

Castiel cocks an eyebrow and leans forward again, but this time his body has a different poise to it. waists touching, flukes brushing, hip fins waving. The heat in Dean’s face grows stronger.

“It could be,” Castiel says softly and Dean would think he was teasing if it wasn’t for how close his lips were to Dean’s. Dean’s breath shudders and he finds his gaze dropping to Castiel’s lips, wondering what it would be like to kiss him, what he would taste like. He dismissed those chaste things last dark as an unbridled mating urge, but what if they… weren’t? The way Castiel is tilting his head suggests just that.

Something warm and bubbly tugs at Dean’s stomach, urging him forward. His heart quickens, slamming against his ribs like it wants to escape his chest. Despite what his head and logic is telling him, Dean wants to chase the warmth bleeding from Castiel’s lips. It’s not something he could indulge himself in even if he wanted to, but the appeal of a kiss is growing rapidly as the heartbeats tick by.

But then Castiel breaks the moment and puts his hand on Dean’s shoulder, expression going serious.

“Dean, do you trust me?”

Dean blinks. The mood takes a steep dive from flirty to formal. “What?”

“Do you _trust_ me?”

“Um.” Dean swallows. Inexplicably, he does. Not completely, and not as much as Sammy, but he’s already damaged goods in that category. This is as good as it gets. “Yeah, I guess so.”

“Good.” Castiel crowds Dean back and down until he sinks to the floor, tail curling around himself to keep his balance as Castiel follows him, resting their chests together. Dean ducks his head so all Castiel can see is his hair, not the redness he can feel creeping up his cheeks. He’s still not used to the closeness and his skin feels too tight when Castiel holds his gaze this close. 

Instead of forcefully tipping his head up, Castiel just nuzzles Dean’s hair and strokes down his arms, fingers gentle and soft and trailing small bumps. Dean shifts nervously as those hands continue downward, brushing along the bones in his wrists and over the backs of his hands and fingers to trace along the place where torso meets tail. He can already feel Castiel’s sheath starting to bulge, but Dean himself remains unresponsive. It’s hard to become aroused when he knows all that awaits him is discomfort.

At Dean’s lack of response to his playful hands, Castiel nibbles at the tips of his ear fans, then descends to his gills. The effect is the same as last time, pleasant and thrilling. Dean lets out a small gasp and clenches his fists, back fin flexing as a shiver runs down his spine.

But Castiel doesn’t stop at his there. After a few heartbeats of gentle biting and licking Dean’s gills, Castiel continues down his neck. He gives Dean’s shoulders and chest the same attention, taking his time covering the span of Dean’s chest with his tongue and teeth. Despite the fact that Castiel can no doubt feel Dean’s sheath swelling against his stomach, he doesn’t even pause to glance down at him, just continues teasing at the skin of his chest. 

His nipples and the creases of his muscles seem to draw the most of Castiel’s efforts, probably because those places make the most noises slip out of Dean. Castiel also sucks a few marks into the soft blubber on his stomach to match the one on his neck. They darken into existence mere heartbeats after Castiel pulls his mouth away with a small, satisfied grin. It doesn’t feel as good as other things Castiel did, but a matching smile flits across Dean’s lips. Reef folk may not put much thought behind conserving energy for the cool season, but to a kelp folk, and blubber is a sign of a clever hunter who has the skill and foresight to catch more than they need.

Castiel’s hands follow where his lips were, tracing swirling patterns over Dean’s skin. The blush, almost gone now, comes raging back full force and bleeds down his neck into his chest. This is more attention than anyone has paid Dean is a long, long time. It’s overwhelming. He just met Castiel last dark and already he’s treating him like something sacred. Each gentle touch to scarred skin makes Dean’s heart squeeze and his breath shudder. 

Even when Castiel reaches Dean’s tail, he doesn’t immediately go for his slit. Castiel continues to lavish  
his tail with licks and scrapes of teeth that Dean can barely feel through his scales. It’s more of a gesture than an action that supposed to bring pleasure, though. All folk, reef and kelp folk alike, put great pride in their scales and Dean is no exception. He sighs and runs a hand through Castiel’s hand, the strands tickling the skin between his fingers.

At Dean’s touch, Castiel abandons the teasing and glances up at Dean through his lashes as he slides up Dean’s tail to hover over his slit, hands poised on either side to hold him down. Dean holds his breath at the first swipe of Castiel’s tongue, but it all comes rushing out at the second and he lets his head fall back after that. 

By the time Castiel’s managed to loosen him up enough to dip his tongue in, Dean’s sheath is throbbing and twitching and his fins are flexing uncontrollably. Dean groans when Castiel brings his fingers into the teasing and has to pinch his side fin to keep himself under control. If he allows himself to unsheath, Castiel won’t be able to fit inside him. 

“Cas,” Dean groans. It’s like trying to stop a tsunami with his bare hands. “You gotta stop that.”

“Why?” Castiel asks, licking at Dean again. Dean moans at the raspy feel of it on the sensitive flesh of his slit. 

“Because,” he says, voice rough with arousal and embarrassment. “You won’t fit.”

“Ah, but that is where you are wrong.” He does something far too clever with his tongue that has Dean arching his back and making a strangled sound of surprised pleasure. 

“What?”

Castiel grins up at him and places a hand to his chest, gently pushing until Dean allows himself to be pushed back onto the alcove floor. The pebbles dig into his back fin and skin, but this way Castiel can prop himself up over Dean on his elbows and wind their tails together. His sheath rubs against Dean’s and they both shudder, Castiel humming contently. 

“You are wrong,” Castiel repeats. He slips a hand between them and massages Dean’s sheath with hard presses of his fingers. Dean shifts into the pressure even though it’s just going to make him lose himself faster. When his mind is flooded with pleasure it’s hard to think clearly. 

A shiver from Castiel and the new press of warmth against his tail tells Dean that Castiel is unsheathed. Dean sighs and settles back onto the rocks, resigning himself to what comes next, but Castiel’s fingers just press into him harder. A gargled yelp bursts from Dean’s lips and before he knows what’s happening, he’s sliding out into Castiel’s waiting hand. 

There’s no time to apologize or reprimand himself for the wasted opportunity to mate because Castiel is working his fingers over Dean’s dick just as skillfully as he had teased his slit. Dean grabs his shoulders, tail squeezing around Castiel’s, as confusion and pleasure swirl around unrestrained inside him. He’s climaxed by his own hand plenty of times before, but the feel of Castiel’s long, soft fingers is much different than his own calloused hand. Castiel watches him closely as he writhes, eyes locked on Dean’s face to find whatever he’s searching for.

“It is good?” he asks finally, thumbing over the head of Dean’s dick.

“Yeah,” Dean manages to choke out. “But why-”

“I am told,” Castiel says and he finally stops stroking Dean, lining himself up instead. The top of his dick bumps into the underside of Dean’s. “That it is far more enjoyable when unsheathed.”

Dean’s hold on Castiel’s shoulder tightens and he glances down at where Castiel is pressing into him. “But you won’t-”

Castiel silences him with a hand to his lips. “You trust me.”

After a heartbeat, Dean gives a small nod. The hand against his lips slips away to rest against his cheek instead and Castiel bends his head down to touch their foreheads together.

“Good,” he says. 

Then he pushes in and Dean’s whole world explodes. 

[](http://www.dazzlejunction.com/generators/image-generator.php)

_Anael and a quick pen sketch of her crown because I had five minutes and was bored (how do you draw tiny braids)_  


**Notes for the Chapter:**

> Sorry this chapter took so long to upload, guys! After school ended two weeks ago I had some personal shit I needed to take care of. I might have a new chapter up before I leave on vacation, but if not I'll be going on a hiatus until early August.


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